The invention relates to an adjustable-backset latch system for locksets, and a method for adjusting backset and assembling the latch system. The latch system enables the user to quickly change a backset by the usual backset increment of xe2x85x9cxe2x80x3 by simply moving a pin through a xe2x80x9cUxe2x80x9d-shaped slot in a housing member without having to rotate any of the components of the backset latch system. The invention also includes improved deadlatching and bolt retraction systems. The invention also includes the combination of the latch system with a lockset.
Existing latch arrangements for varying the backset from 2xe2x85x9cxe2x80x3 to 2xc2xexe2x80x3 (and vice-versa) for locksets using both deadbolts and deadlatching systems are well known. Conventional adjustable-backset latch systems have one or more of the following characteristics. The backset adjustment is not easy to use; there are loose parts, often contributing to jamming. They do not fit into a xe2x85x9exe2x80x3 diameter hole; they do not interface with half-round spindles in a pull-type fashion using horizontal stems extending from the lockset rose or rose liner. In addition, by locating the backset-adjusting components near the inward half of the latch, not enough material is left in the latch subassembly for a xe2x85x9exe2x80x3 latch to provide the desired structural strength to meet Grade 2 standards specified under ANSI/BHMA 156.2. Furthermore, their design is such that if the various actions and cooperation does not occur in proper sequence, the mechanism jams. In other cases, the user must rotate one part of the latch system relative to another to move both a housing portion and a bolt portion simultaneously by the same backset distance, a maneuver which usually takes two hands. In other systems, parts are removeable, and are easily lost. Still others are not easily retrofittable for existing installations unless further modifications to the existing locksets are made. Still further, they may be designed in such a way as to make it difficult to automate the manufacturing or assembly of their components. In short, there is a need for a Grade 2 adjustable backset latch system for a pull-type mechanism (in which linkages move in the same direction as bolt retraction) that is strong and durable. There is still another need for a backset latch system in which the backset may be quickly adjusted by the user with a motion of just one hand. Also, the latch system needs to be designed in such a way as to be easily assembled using automated procedures. Finally, there exists a need for an adjustable backset latch system in which the timing and operation of the respective components are consistently reliable.
Accordingly, it is a particular object of the preferred embodiments of the invention to provide an adjustable-backset latch system, and method, in which the user need only move a detent pin along a xe2x80x9cUxe2x80x9d-shaped slot in the latch housing to change the backset, without affecting the ability of a bolt operator to retract the latch bolt. It is another object of the present invention to provide a unique adjuster for coordinating the timing and operation of a bolt retraction system and a backset adjustment system. It is still another object of the present invention to provide an improved deadlatching system in which a deadlocking dog cooperates with a housing and a latch bolt and an auxiliary bolt to reliably and consistently provide the deadlatching function. It is still another object of the present invention to enable the components of the system of the present invention to be assembled using automated manufacturing techniques. It is still another object of the present invention to provide methods for the user to retract the bolt and adjust the backset of the systems of the present invention. A feature by which the above objects can be obtained is by providing a resilient adjuster mounted in one of a set of inner and outer cases which releasably couples the inner and outer cases and front and back links, which together make up a bolt actuator. Preferably, the adjuster includes a member which is engageable by a person to cause the adjuster both to uncouple the cases and links, and to simultaneously adjust the links and cases by a predetermined backset increment. Another feature by which the above objects can be attained is by providing a bolt actuation system in which the bolt actuator, responsive to rotation of a bolt operator retracts a linkage that pulls a cam against a portion of the bolt, in such a manner as to multiply the linear travel of the bolt operator to achieve complete bolt retraction. Still another feature by which the above objects can be attained is by providing a deadlatching system in which a spring dog is mounted between a deadlocking dog and an auxiliary bolt such that not only is the auxiliary bolt biased normally to its extended position, but the deadlocking dog is simultaneously biased to a position which blocks the retraction of a main bolt. Still other features by which the above objects may be attained is by forming fastener clearance holes in both the housing and the adjuster, thereby yielding a compact yet structurally sound system.
And furthermore, still another object of the present invention is to provide a lockset having one or more handles and knobs which uses one or more elements of the adjuster-backset latch of the present invention.
Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings.